On Monday, February 6, 2012 at 2:55 PM, Cole Robinson wrote:

On 02/06/2012 12:34 PM, Michael DeHaan wrote:

On Monday, February 6, 2012 at 11:37 AM, Cole Robinson wrote:

On 02/06/2012 10:58 AM, Michael DeHaan wrote:

Cole --

What's the workaround to auto-start Xen PV's? (or is there not a way?)

Seems like we could just implement this however needed (if xenpv… do this

instead…), if virtinstall won't do it for us.

The autostarting code could just be conditionally enabled if virt-install is

new enough (just a grep of the help output) so that's not the issue.

The issue is that current koan code manually passed a kernel + initrd for the

PV guest to boot. That's the only install scenario for PV guests AFAICT. And

this is only available via the virt-install in a version newer than what's in

RHEL5.

That's also how the virt installs work for everything else in koan, including

qemu/KVM.

(Maybe I'm misunderstanding something?)

This is my understanding of the current code.

Xen FV: always does a PXE boot (so guest is actually talking to PXE server):

https://github.com/cobbler/cobbler/blob/master/koan/xencreate.py#L80

Xen PV: Libvirt tells the guest to boot directly off the kernel/initrd pair

specified in profile_data["kernel_local"] and profile_data["initrd_local"]:

https://github.com/cobbler/cobbler/blob/master/koan/xencreate.py#L88

(are those kernel_local + initrd_local values filled in by cobbler or does the

user need to manually specify them?)

QEMU/KVM has two install options:

if profile_data["file"] is present, boot off it like a cdrom:

https://github.com/cobbler/cobbler/blob/master/koan/qcreate.py#L101

if profile_data["install_tree"] is present, pass the URL off to virtinst and

have it use it's tree probing to fetch kernel + initrd:

https://github.com/cobbler/cobbler/blob/master/koan/qcreate.py#L121

 

My implementation preserves this behavior, but in reality Xen FV and Qemu can

all boot from tree/kernel, cdrom, and pxe. Xen pv can only boot from

tree/kernel (which is the same thing basically).

My suggestion was to adapt xen pv to behave as qemu does with "install_tree".

The workaround could be to make PV installs work like qcreate install_location

installs, which is basically the same as direct kernel/initrd boot but you

rely on virt-install to pull the kernel/initrd from the install tree.

Just trying to make sure this wouldn't break anyone.

The install tree location isn't actually required in Cobbler, it's only a

parameter to the kickstart … Are you saying we'd have to use the install

tree method *only* for Xen PV? If so, that might be an acceptable

limitation… if Xen FV or qemu/KVM requires the tree to find the

kernel/initrd that seems bad to me, because we deal with a lot of arbitrary

distros that express install tree locations in different ways.

ks_meta["tree"] gives you this if someone had ran "Cobbler import" previously.

If we can avoid using that when we don't have to, that would be good…

Since

cobbler tracks this info it would probably 'just work' with a tiny patch but

someone would need to test. And this has been supported on virt-install

command line since probably rhel5.1

"it" == making autostart work for Xen PV, right?

No, autostart is not the issue here. The issue is getting guests to actually

install. The autostart piece is just recent functionality to cobbler that

currently brok all installs on RHEL5 host. Fixing this would be a fairly

trivial patch on top of current koan or my code.

The more interesting piece is making xen PV installs actually work on RHEL5

where virt-install is not new enough to provide the cli option needed to have

parity with current xen PV installation, which requires passing a local kernel

+ initrd path to boot from.

Sorry if that isn't clear.

Thanks,

Cole